A wide variety of fluid absorbent structures known in the art absorb body fluids such as blood, urine, menses, and the like, and are sanitary and comfortable in use. Disposable products of this type generally comprise fluid-permeable topsheet material, fluid absorbent core, and fluid-impermeable backsheet material. Various shapes, sizes and thicknesses of such articles have been explored in an attempt to make their use more comfortable and convenient.
Odor control in sanitary products has been under investigation for many years. Many body fluids have an unpleasant order, or develop such odors when in contact with air and/or bacteria for prolonged periods.
Various odor-controlling agents have been disclosed in the literature. For example, U.S. Pat. No. 4,525,410, Hagiwara et al., issued Jun. 25, 1985, teaches zeolite particles (doped with bactericidal cations) assertedly stably held in a fibrous web by incorporating some portion of meltable fibers in the web, and applying heat. These compositions can be used as the "outside cover layer" in, e.g., "general sanitary goods".
U.S. Pat. No. 2,690,415, F. A. Shuler, issued Sep. 28, 1954, teaches particles of odor-absorbing materials uniformly affixed at the interstices of a permeable web by adhesive to provide an odor absorbent medium for, e.g., catamenials. Particulate carbon, silica gel and activated alumina are noted. Shifting/displacement of the particulates is assertedly avoided and the sheet is flexible.
ABSCENTS (odor-control molecular sieve from Union Carbide) for use in diapers and catamenials are specifically noted in Union Carbide brochure (A. J. Gioffre 1988). The brochure indicates that UC's market research shows potential benefits in such products. U.S. Pat. Nos. 4,795,482 and 4,826,497, relate to ABSCENTS used as an odor-controlling agent, generally, and in sanitary products, in particular.
Activated carbon is a very effective odor absorber, with average internal surface area of about 1000 m.sup.2 /g. However, with its intense black color, activated carbon is less readily incorporated into consumer products.
Zeolites have smaller surface area, in the range of about 400-800 m.sup.2 /g. They are white or have light color, and thus are aesthetically acceptable. However, zeolites may absorb the moisture in body fluids (i.e., water) over other fluids, which may compromise its effectiveness. Furthermore, activated carbon and zeolites have open structures, and continuously absorb airborne organic vapor, unless hermetically sealed. Therefore, during storage, these odor adsorbents can become saturated and less efficient before the products are used.
Some consumers prefer catamenial and diaper products, etc., that have a "scent signal" in addition to odor control. A "scent signal" is a positive perfume odor which signals the removal of odor during use of the product. This scent signal is normally difficult to provide because odor absorbents can react with and/or deplete the perfume in the article prior to use, and the absorbents themselves can become inactive.
A consumer's ability to notice their own body odor, both good and bad, decreases after prolonged exposure to the odor making it difficult for them to evaluate the efficacy of odor removal products. In other words, consumers become habituated to constant odors. Therefore, the positive odor is preferably fleeting and is delivered in "bursts" during use to avoid habituation to the positive signal. The "scent signal" signifies the removal of odor so the consumer can feel greater self-confidence.